The idea of sigil is however quite widespread. Many languages have special chars as starting or ending variable names to indicate special purpose, though, mostly as a convention only, not part of the language machinery.

For example:

Python class names always start with CapitalLetter. This is by convention.

OCaml variable must start with lower case.

In many languages, by convention, variable start with _ means it's not used.

In many languages, by convention, variable start with double _ means it's internal.